1. Field of the Invention
The present invention relates to a novel metal working oil composition. More specifically, it relates to a metal working oil composition which is particularly suitable as a press lubricant for aluminum alloys and which is more excellent in coating workability, lubricity, degreasing properties, weldability and the like than a conventional solid coating type lubricant.
2. Description of the Related Art
In recent years, high-strength aluminum alloys have admirably been used as materials for parts of cars, rolling stocks, ships, airplanes and the like from the viewpoint of weight lightening which leads to fuel saving. Since these high-strength aluminum alloys are poor in plastic workability, an acrylic polymer-based or a wax-based solid coating type lubricant has usually been used as a working lubricant.
However, the solid coating type lubricant is poor in mass workability and insufficient in coating workability, lubricity, degreasing properties and weldability in view of (1) that a coating system (a roll coater and a drying step) is additionally required to be installed in a plate manufacturing process, (2) that the coating film is liable to partially peel by contact peeling and blocking, and the partial peeling is not restorable, which causes press failure, (3) that a degreased film floats in a tank, and in consequence, the service life of a degreasing liquid is shortened, and (4) that welding failure is more liable to occur as compared with an oil system (particularly in the case of a resin coating type).
If a liquid press lubricant having a low viscosity is developed which can solve the above-mentioned problems of the conventional solid coating type lubricant and which is excellent in mass workability, the aluminum materials can be applied to car bodies and the like by the use of this liquid press lubricant, whereby the liquid press lubricant can contribute to an industrial field in points of energy saving and the like.